372 
Spratt. — Some Observations on the 
Marx, Massart, Fischer, and Palla, have failed to find any nuclear structure 
in the central body present in the cyanophyceous cell ; but Wille, Scotland 
Zacharias in his later work, have shown it to be of a nuclear character. 
Hegler says that it consists of a faintly stainable ground substance in which 
is embedded a small quantity of chromatin, but it possesses no nuclear 
membrane or nucleolus. Wager and Kohl have confirmed his observa- 
tions, and in Anabaena Cycadeae also there does not appear to be any true 
nuclear membrane or nucleolus. Occasionally, however, such forms as 
Figs. 5 and 6 (PI. XXXII) have been observed where a body somewhat 
resembling a nucleolus is present, and in Fig. 5 there almost appears to be a 
rudimentary membrane. Irregular forms similar to those described by Kohl 
have also been noticed (Figs. 6 and 7). The central body contains albu- 
minous material, which takes up methyl green, gentian violet, carbol fuchsin, 
and to some extent haematoxylin. It is present as granules, which vary 
both in size and number (F'igs. 5, 6, and 7). The vegetative cells contain 
from one to five, whilst in the spores they are typically more abundant 
(Fig. 7), but may apparently be collected into one large granule (Figs. 5 
and 6). Kohl found pectin substances, and also some which assumed a 
blue-black colour when treated with chloriodide of zinc, present. In Anabaena 
Cycadeae the former are indicated by the blue colour produced with haema- 
toxylin, but no visible effect was obtained with chloriodide of zinc, even 
after forty-eight hours’ immersion in this fluid. 
The chief product of photosynthesis is glycogen, which is indicated by 
the reddish brown colour produced in the peripheral cytoplasm by treat- 
ment with iodine in potassium iodide ; the colour being removable by the 
solution of the glycogen in water, unless the material has been previously 
treated with alcohol. Oil is frequently present in the form of very minute 
drops in the heterocysts and spores, as shown by the black colour produced 
in the presence of osmic acid. 
A number of very distinct granules are present in the cytoplasm, which 
represent reserve albuminous material, and have been called cyanophycin 
granules. Zukal described them as distinctly differentiated portions of the 
protoplasm, and Hieronymus found them to contain nitrogen and phos- 
phorus. They certainly appear to grow during the life of the cell, being 
larger in old cells and spores. This, with their disappearance in nodules 
kept in somewhat unfavourable conditions, is quite in agreement with their 
being reserve food material. They are most effectively stained by pro- 
longed treatment with an alcoholic solution of eosin, when they become 
deep red. They swell and eventually disappear in dilute acids or caustic 
potash, become deep brown with iodine in potassium iodide followed by 
sulphuric acid, and are unaffected by alcohol, xylol, ether, Millon’s reagent, 
or chloriodide of zinc. These granules are very abundant in the vegetative 
cells and spores (Fig. 8). In young heterocysts the terminal granules, and 
